Non-metallized and subtoichiometric metallized reactions with ammonia and other weak bases in the dehalogenation of refrigerants

ABSTRACT

Ozone depleting fluorocarbon compounds are dehalogenated through more economic reduction reaction with solvated electrons formed from lower equivalents of reactive metals than previously used by reacting the partial reduction products with non-aqueous liquid nitrogen-containing bases, such as ammonia, or alternatively, without any reactive metal by reacting with the base alone. Mixtures of fluorocarbon refrigerants including difficult to separate azeotropes of dichlorodifluoromethane contaminated with chlorodifluoromethane are reclaimed by treating only with weak non-aqueous nitrogen-containing bases to provide essentially chemically pure dichlorodifluoromethane refrigerant suitable for recycling/reuse.

TECHNICAL FIELD

The present invention relates generally to methods of treating ozonedepleting substances, and more specifically, to methods of decomposingand purifying chlorofluorocarbon (CFC) refrigerants.

BACKGROUND OF THE INVENTION

Chlorofluorocarbons (CFCs) are synthetic chemical compounds widely usedin refrigeration and air conditioning; as aerosol propellants andsolvents; in forming foams, including those used in fast-food packaging;and in rigid insulation. Scientists now view these synthetic chemicalsas the main threat to Earth's protective ozone layer. Because CFCs areimmune to destruction in the troposphere, and because they eventuallyfloat upwardly, their manufacture and release have lead to theaccumulation of large amounts in the stratosphere. In the stratosphere,CFCs are broken down by sunlight into chlorine, which has a catalyticand destructive effect on ozone. The result has been a significantdecline in the global ozone shield and an increase in the amount ofharmful ultraviolet radiation reaching the surface of Earth. Accordingto a United Nations' study, every 1 percent drop in ozone will lead to a3 percent increase in non-melanoma skin cancers in light-skinned people,as well as dramatic increases in cataracts, lethal melanoma cancers, anddamage to the human immune system. Higher levels of UV light may alsoworsen ground-level pollution and hurt plants, animals, and especiallylight sensitive aquatic organisms.

As a result, destruction of CFCs, and in some instances, reclamation ofCFC refrigerants is a vital component of the national and globalstrategies for protection of the earth's ozone layer in a mannerconsistent with minimal economic disruptions associated with thephase-out of this class of chemicals. There are still sizable reservesof CFCs on hand which must be treated and converted to environmentallybenign substances. Likewise, until existing refrigeration and airconditioning equipment is replaced or retrofitted with devices which arecapable of operating with more environmentally friendly refrigerants, asCFC production is curtailed and eventually eliminated, industry andconsumers must rely increasingly on the availability of reclaimedrefrigerants.

Various methods have been proposed for the destruction of unwanted CFCs,such as thermal oxidation, catalytic decomposition, supercritical wateroxidation, plasma destruction methods, biological processes, UVphotolysis, to name but a few. Many are either in experimental stages ofdevelopment, economically unattractive or incapable of selectivelydecomposing only specifically targeted compounds.

One other method for the destruction of CFCs is disclosed in U.S. Pat.No. 5,110,364 by Mazur et al, which provides for chemically degradingunwanted CFCs by dehalogenation reactions through solvated electronchemistry. Mazur et al disclose the formation of solvated electronsthrough dissolving metal reactions with nitrogen-containing bases, suchas ammonia wherein at least one chlorine atom of the CFC compound isremoved during the reaction to yield products having reducedenvironmental impact. A somewhat related process is also described inJapanese unexamined application 59-10329 (1984) to Showa Denko KK.Contrary to the disclosures of the earlier Showa Denko process, Mazur etal discovered the reduction of CFCs or other chlorinated organics, e.g.PCBs, with solvated electrons could be successfully carried out in thepresence of substances previously thought to interfere with thestability of the solvated electrons or selectivity of the reaction.Mazur et al discovered the need for removing previously consideredcompeting substances, such as oxygen, carbon dioxide, water, etc., fromthe reaction mixture was not required, and such costly pretreatmentstep(s) could be omitted.

While solvated electrons provide a practical solution for disposing offluorocarbon compounds, including CFCs, in practice metal consumptionand solvent requirements, e.g. sodium and ammonia are significant costelements. Together, the two can make up as much as 70 percent of totaloperating costs. Of the two main reactants, ammonia is the far lesscostly, and processes for ammonia recovery are available. However,metals such as calcium, sodium and potassium are non-recoverable, andmore costly consumable reactants which can detract from economics of theprocess.

Accordingly, it would be highly desirable to have an improved moreeconomic process for the dehalogenation and destruction offluorocarbons, or in the reclamation of certain refrigerants wherein thenormal stoichiometric equivalents of metal reactant to refrigerantpreviously required to dehalogenate targeted compounds are significantlyreduced, and in some instances, metal requirements entirely eliminatedfrom the process.

SUMMARY OF THE INVENTION

The term "refrigerant" as used throughout the specification and claimsis intended to mean fluorocarbon compounds as a class of chemicals whichare suitable for use in refrigeration and air conditioning equipment.Likewise, the term is also intended to include fluorocarbons which areuseful as solvents, aerosol propellants, in manufacturing syntheticfoams, packaging, insulation, and the like. Thus, it should beunderstood the term "refrigerant" is intended to embrace a broader rangeof fluorocarbons then merely those which are suitable for airconditioning and refrigeration applications. They include productscommercially available under trademarks, such as Freon, Halon, Frigen,Arcton, Genetron and Isotron.

It is a principal object of the invention to provide a method fordehalogenating refrigerants, and more particularly, hydrofluorocarbonrefrigerants where instead of relying on the dissolution of a reactivemetal in liquid ammonia or other nitrogen-containing base in theformation of solvated electrons, the improved method provides for thesteps of:

(a) providing a fluoroalkane refrigerant having at least one hydrogenatom and at least one other halogen atom in addition to fluorine, and

(b) in the absence of a dissolving metal reactant reacting thefluoroalkane refrigerant with only the nitrogen-containing base which isnon-aqueous to decompose the refrigerant.

Fluoroalkane as recited above is intended to mean hydrofluorocarbonshaving in addition to a hydrogen atom, at least one other halogen atomin addition to fluorine, i.e., chlorine, bromine and/or iodine.Surprisingly, it was found that weak non-aqueous nitrogen-containingbases, like ammonia are capable of removing chlorine, bromine and iodineatoms from hydrofluorocarbon molecules at ambient temperature conditionswithout first forming solvated electrons in dissolving metal reactionswith sodium or other reactive metals, such as aluminum. That is to say,it was found that the ozone depleting properties of certain refrigerantscan be eliminated without introducing metal into the process. Inaddition to more attractive economics of the process, any potentialhazards associated with handling, transporting and storage of highlyreactive alkali metals are avoided.

It is yet a further object of the invention to selectively dehalogenatecompositions having a plurality of refrigerant compounds. Accordingly,the invention also contemplates reclamation methods wherein fluorocarbonrefrigerant-containing mixtures which have become contaminated withfluoroalkane refrigerant compounds are effectively purified. The methodis carried out by the steps of:

(a) providing a composition with at least two refrigerants, (i) aprimary perhalogenated compound and (ii) a contaminating fluoroalkanecompound having at least one hydrogen atom and at least one otherhalogen atom in addition to fluorine;

(b) reacting the refrigerant composition of step (a) with a weak base,namely a non-aqueous nitrogen-containing compound, such as ammonia toselectively decompose the contaminating fluoroalkane refrigerantcompound (ii), and

(c) recovering a refrigerant composition from the reaction mixture ofstep (b), the composition comprising the primary perhalogenatedrefrigerant compound (i). The recovered composition is sufficiently freeof the contaminating fluoroalkane refrigerant (ii) to enablerecycling/reuse.

This aspect of the invention is particularly unique in view of thediscovery that weak nitrogen-containing bases are capable of selectivelydehalogenating hydrofluorocarbons without also reacting with the primaryfluorocarbon compounds. The selectivity of the process is alsosignificant in permitting the recovery of refrigerants from mixtureswhich otherwise could not be readily purified through distillationmethods because of their forming azeotropes with other refrigerants.Heretofore, such azeotropes were disposed of by decomposing the entiremixture since there was no practical and economic means for separationand recovery of the still useful refrigerant compounds.

It is still a further object of the invention to provide for an improvedmethod of dehalogenating fluorocarbon refrigerants by a reductionmechanism through dissolving metal reaction in a nitrogen-containingbase, such as ammonia. Unlike earlier methods for the destruction ofunwanted ozone depleting perhalogenated refrigerants with solvatedelectrons which typically employed 8 equivalents of reactive metal permole of refrigerant, it was discovered that dehalogenation of suchrefrigerants could be effectively performed with only a fraction of themetal previously used, thereby making the process economically moreattractive. The improved method includes the steps of:

(a) providing a perhalogenated fluorocarbon refrigerant having at leastone other halogen atom in addition to fluorine, e.g. chlorine, bromineand iodine;

(b) forming a solution of solvated electrons by dissolving in ammonia orother weak nitrogen-containing base a substoichiometric amount of areactive metal in an amount sufficient to reduce the perhalogenatedrefrigerant by removing the other halogen atom therefrom;

(c) reacting the refrigerant of step (a) in the solution of solvatedelectrons of step (b), the reaction being conducted at temperaturessufficiently low as to retard reactions of the solvated electrons andliquid ammonia or other nitrogen-containing base with by-products of thereduction reaction, and

(d) elevating the temperature of the reaction mixture of step (c) toinitiate further dehalogenation by reacting with the ammonia or othernitrogen-containing base to form compounds which are non-ozonedepleting.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Methods of the invention include the dehalogenation and destruction of"fluoroalkane" refrigerants which term for purposes of this invention isintended to mean principally fluoromethane type refrigerants, but alsofluoroethane types. The fluoroalkane refrigerants have at least onehydrogen atom and one other halogen atom in addition to fluorine, namelychlorine, bromine and/or iodine. Representative fluoroalkane typesinclude refrigerants available under the E.I. dupont trademark Freon®,such as Freon 22 (chlorodifluoromethane), Freon 21(fluorodichloromethane), Freon 31 (chlorofluoromethane), Freon 31B1(bromofluoromethane), Freon 22B1 (bromodifluoromethane), and mixtures ofthe same. Other fluoroalkane refrigerants include, for instance,1,1,2,2-tetrachloro-2-fluoroethane (FC-121);1,1,1-trifluoro-2,2-dichloroethane (FC-123).

One preferred embodiment of the invention includes reacting theforegoing fluoroalkane refrigerants with a non-aqueousnitrogen-containing base. The expression "non-aqueousnitrogen-containing base", or similar variations thereof as appearing inthe specification and claims is intended to mean substantially free ofwater. That is to say, the expression is intended to denote anhydrousbases which are free of any water, but also nitrogen-containing baseshaving small or minor amounts of water ranging from 3 percent or less,which may be present, for example, as an impurity.

Representative examples of non-aqueous nitrogen-containing bases includemainly ammonia, i.e. anhydrous liquid ammonia and liquid ammonia havingminor amounts of water, i.e. 3 percent or less. Other suitablenon-aqueous nitrogen-containing bases in addition to ammonia which maybe employed in the dehalogenation of fluoroalkane refrigerants includeprimary amines, secondary amines, tertiary amines, cyclic amines,heterocyclic alkyl mono and polyamines and mixtures thereof.Representative examples of such bases include methyl amine, ethyl amine,dimethyl amine, diethyl amine, triethyl amine, n-propyl amine,piperidine, morpholine and ethylenediamine.

The foregoing nitrogen-containing bases are weak bases. For purposes ofthis invention the expression "weak base" is generally intended toencompass mainly nitrogen-containing bases having a pK_(b) in the rangeof 2 to 5.

The non-aqueous nitrogen-containing bases are suitable for use as is, orthey may be mixed with other organic solvents provided the solvents aresubstantially soluble in the refrigerant, and do not react with thebase. Representative examples of suitable organic solvents includeprimary alcohols, such as methanol, ethanol, propanol, butanol;secondary alcohols like 2-propanol; ethers, such as diethyl ether and1,4-dioxane; glycol monoethers like methoxyethanol and butoxypropanol;nitriles, such as acetonitrile, and amides like N,N-dimethylformamide orN,N-dimethylacetamide.

Dehalogenation of fluoroalkanes with non-aqueous nitrogen-containingbases is readily performed in a pressure vessel at ambient temperatureconditions, which includes temperatures generally in the range of about10° to about 70° C. The concentration of the nitrogen-containing baseemployed is generally in the range of about 10 percent to about 100percent. The reactions are preferably conducted under anaerobicconditions. A means of removing insoluble reaction products (salts) byfiltration is provided.

As a further preferred embodiment, the invention includes methods forselective dehalogenation of refrigerant compositions containing two ormore refrigerants. More particularly, the invention includes methods forpurification of refrigerant compositions containing useful primaryrefrigerants which have become contaminated with other refrigerants.Expressions like "primary refrigerant" and "primary perhalogenatedrefrigerant" as appearing herein are used to denote the specificrefrigerant(s) desired for recovery from contaminated refrigerantmixtures in the dehalogenation process. Primary refrigerants includemainly refrigerants which are perhalogenated, or in other words,fluorocarbon refrigerants in which all the carbons are fully substitutedwith halogen atoms. They include such representative examples as Freon®11 (fluorotrichloromethane), Freon 12 (dichlorodifluoromethane), Freon 3(chlorotrifluoromethane), Freon 14 (tetrafluoromethane), Freon 13B1(bromotrifluoromethane), and so on.

The expression "other refrigerant" is used herein to denote thecontaminating or unwanted refrigerant portion to be eliminated fromrefrigerant compositions containing the primary refrigerant. Otherrefrigerants correspond to the "fluoroalkane refrigerants" previouslydiscussed in connection with the first embodiment of the invention, andincludes fluorocarbon compounds having at least one hydrogen atom and atleast one other halogen atom in addition to fluorine, e.g. chlorine,bromine and/or iodine. Representative examples includechlorodifluoromethane, fluorodichloromethane, chlorofluoromethane,bromofluoromethane, bromodifluoromethane, and mixtures of the same.

This second embodiment of the invention is useful in reclaimingrefrigerant compositions. In order to qualify for reuse, reclaimedrefrigerants are required to meet the American Refrigeration Institute's"700" specifications which stipulate the permissible levels ofcontaminants. That is, strict limits are placed on moisture,particulates, acidity, oil content, non-condensible gases, and otherrefrigerants present. Existing reclamation processes are capable ofmeeting all of the foregoing criteria with the exception of "otherrefrigerants", which are not permitted to exceed 0.5 percent maximum.

Hence, the second embodiment of the invention is useful in treatingmixtures of fluorocarbon compounds, including those contaminatedwith >0.5 percent of other refrigerant. However, methods of the presentinvention are also effective in treating compositions containing minoror even trace amounts, i.e., <0.5 percent other refrigerant(s). Onerepresentative example of a widely found refrigerant mixture isdichlorodifluoromethane also known as Freon® 12 or FC-12, which isfrequently contaminated with Freon 22 or chlorodifluoromethane, bothhereinafter called R-12 and R-22, respectively. Although removal of theunwanted R-22 contaminant from such a mixture would appear to be readilyaccomplished by distillation due to differences in their boiling points(R-12 b.p. -29.8° C. and R-22 b.p. -41° C.), separation by distillationis not readily achieved due to the formation of an azeotrope consistingof 75 percent R-22, when the two refrigerants become mixed.

The principal object of this embodiment of the invention is theselective chemical decomposition of other refrigerants in compositionsof refrigerant mixtures without loss of the primary refrigerant. Thisincludes the steps of separation and recovery of the compositioncontaining the primary refrigerant from the reaction medium in a refinedor purified state free or virtually free of other refrigerant, so as tomeet ARI specifications for other refrigerants. The methods of thissecond embodiment are especially useful in recycling discontinued orpotentially scarce refrigerant compounds.

While the methods of the invention are especially useful in thereclamation of contaminated perhalomethane type primary refrigerants theinvention contemplates the purification and recovery of otherperhaloalkane primary refrigerants as well, such as the fluoroethanesand fluorobutanes. Representative examples include fluorocarbon orFC-112 (1,1,2,2-tetrachloro-1,2-difluoroethane), FC-113(1,1,2-trichloro-1,2,2-trifluoroethane), and the like.

In addition to the reclamation of refrigerant compositions comprising asingle perhalogenated primary refrigerant contaminated with otherrefrigerant(s), the invention contemplates the purification ofrefrigerant mixtures having similar boiling points, and particularlyazeotrope refrigerants, like Freon 500 (dichlorodifluoromethane and2,2-difluoroethane), Freon-503 (trifluoromethane andchlorotrifluoromethane), and particularly an azeotrope ofdichlorodifluoromethane in which chlorodifluoromethane is the otherrefrigerant.

The reaction of the non-aqueous nitrogen-containing base with thecontaminated refrigerant composition is performed in a closed pressurevessel at ambient temperature conditions. The process may be eitherbatch or continuous. With amines of suitably high boiling point purifiedrefrigerant may be separated from the reaction mixture by evaporation.However, with ammonia or low boiling amines the separation isaccomplished by passing the vaporized mixture through water, dilute acidor a sequence of the two to selectively dissolve the amine either as thefree base or as a salt thereof. The refrigerant vapors are thencompressed and cooled to bring it to the liquid state.

As a third embodiment of the invention, fluorocarbon refrigerants, andparticularly perhalogenated types which are not readily dehalogenatedwith weak bases, such as dichlorodifluoromethane,chlorotrifluoromethane, bromotrifluoromethane, and other perhalogenatedfluorocarbons are partially dehalogenated initially through a reductionreaction with solutions of solvated electrons. It was found, thispartial dehalogenation reaction of fluorocarbon refrigerants requires aslittle as one fourth of the reactive metal ordinarily employed inprocesses, such as disclosed by U.S. Pat. No. 5,110,364 and JapaneseUnexamined Application 59-10329 (1984). Such prior methods provide forremoval of all halogen atoms from the perhalomethane refrigerants withstoichiometric amounts of reactive metals, such as sodium in theformation of solvated electrons with ammonia or othernitrogen-containing solvent. Unlike earlier methods, the improvedprocess of the immediate invention provides for the removal of as littleas a single halogen atom, e.g., chlorine, bromine or iodine, therebyrequiring but a fraction of the metal reactant, in view of the lesserrequirement for solvated electrons. With the removal of as little as asingle halogen atom, further dehalogenation of the fluorocarbon isachieved with the remaining available ammonia or othernitrogen-containing base in the reaction mixture.

While not wishing to be held to any specific mechanism of actionrelative to this third embodiment, it is nevertheless believed thatpartial dehalogenation of a perhalocarbon refrigerant by treating in asolution of solvated electrons might result in hydrogenating thestarting refrigerant, and possibly forming an hydrohaloalkaneintermediate which is subject to further dehalogenation throughacid-base reaction with the residual ammonia or othernitrogen-containing base remaining in the reaction mixture.

The solvated electrons are formed in a dissolving metal reaction withammonia or other nitrogen-containing base, such as a fluorocarbonsoluble primary amine, secondary amine or tertiary amine. Specificrepresentative examples were previously provided. The reactive metalsmay consist of alkali metals, such as sodium, potassium and lithium, andalkaline earth metals, like calcium and magnesium. Mixtures of suchmetals may also be employed. Aluminum may also be used as a dissolvingmetal. Compared with the stoichiometric amounts of metal per mole ofperfluorocarbon refrigerant employed according to earlier methods, thepresent invention utilizes 2 mole equivalents of reactive metal per moleof perhalogenated fluorocarbon, or in other words, one fourth of theamount of metal previously required.

Reduction of the perfluorocarbon refrigerant with solvated electrons iscarried out in a closed pressure vessel at temperatures sufficiently lowas to retard reactions which might otherwise occur between by-productsof the reduction reaction and the solvated electrons ornitrogen-containing base. Typically, reactions would be conducted atabout 0° C. or lower. Subsequently the reaction vessel is allowed towarm to ambient temperature which will in-turn initiate furtherdehalogenation of the partially dehalogenated fluorocarbon to completelydehalogenate it, i.e. remove the remaining fluorine, chlorine, bromineand/or iodine atoms as an acid-base reaction with residual ammonia orother nitrogen-containing base.

The following specific examples demonstrate the various embodiments ofthe invention, however, it is to be understood they are for illustrativepurposes only and do not purport to be wholly definitive as toconditions and scope.

EXAMPLE I

In order to demonstrate that a nitrogen-containing base, such as ammoniawas capable of effectively destroying hydrohaloalkane refrigerants inthe absence of a dissolving metal reactant, such as sodium or calcium,an initial experiment was conducted using a reactor consisting of an AceGlass, Inc., heavy walled threaded glass tube fitted with a Teflon®stopper and pressure gauge. The tube was charged with 25.0 g ofanhydrous liquid ammonia (1.5 moles) and 4.1 g of purechlorodifluoromethane refrigerant (R-22). The tube was charged whilebeing cooled in dry ice/isopropyl alcohol (IPA). Once charging wascompleted the tube was sealed and allowed to warm to room temperature.Within 80 minutes after mixing the reactants, salt crystals wereobserved at the bottom of the tube consisting of by-products of thereaction. Additional salts were observed to be continually forming.Within 140 minutes into the experiment the reaction was judged to becomplete and the reactor tube was again cooled in dry ice/IPA to reducepressure in the tube from the ammonia. The pressure gauge was replacedwith a stopper vented through a Teflon tube, and the reaction tube wasallowed to warm. When gas evolution ceased 7.5 g of solids wererecovered. The stoichiometric yield of products was 8.1 g, indicating atleast 93 percent of the R-22 was destroyed in the reaction.

EXAMPLE II

In order to demonstrate the selectivity of weak nitrogen-containingbases in the absence of a dissolving metal, such as potassium orcalcium, in the purification of refrigerant mixtures a furtherexperiment was conducted. 90.5 g of a refrigerant mixture consisting of87.2 percent dichlorodifluoromethane (R-12) and 12.8 percentchlorodifluoromethane (R-22) were charged to a steel tube reactor. Therefrigerant charge thus contained 11.6 g (0.13 moles) of R-22. 24.4 g or1.43 moles of anhydrous liquid ammonia were added to the refrigerantmixture. The reactor tube was sealed and allowed to stand for 3 days atambient temperature conditions. The composition was analyzed, and foundto contain 99.754 percent R-12; 0.105 percent R-22, and a trace of otherrefrigerant (0.141 percent R-32). Analysis showed the reaction to behighly selective in destroying only R-22.

In order to recover substantially pure R-12 from the reaction mixturethe ammonia in the reactor is converted to water soluble salts by theaddition of dilute aqueous sulfuric acid solution. Because of theinsolubility of the R-12 refrigerant in the aqueous salt solution,separate distinct phases form in the reactor consisting of a lowerrefrigerant phase and an upper aqueous phase. The lower refrigerantphase containing the R-12 can be withdrawn so it is substantially freeof the water soluble salts.

EXAMPLE III

To demonstrate the effectiveness of other weak nitrogen-containing basesin dehalogenating hydrohaloalkanes the experiment of Example I wasrepeated using ethylenediamine in place of ammonia. Approximately 5.0 gof chlorodifluoromethane was mixed in the glass pressure tube with about20 ml of ethylenediamine and allowed to warm to room temperature. Avigorous exothermic reaction ensued indicating weak nitrogen-containingbases other than anhydrous liquid ammonia will readily react withhydrohaloalkane refrigerant.

EXAMPLE IV

Dissolving metal reactions with ammonia or other weak base are useful inthe destruction of most refrigerants, including the more stableperhalogenated types. Significantly reduced amounts of dissolving metalsthen previously required can be effectively used to achieve completedestruction of unwanted refrigerants. This can be shown by chargingliquid ammonia to a reaction vessel and allowing it to cool byauto-refrigeration. When a temperature of -10° to -33° C. is reached 2mol equivalents of calcium metal are added and stirred to give thetypical blue solvated electron solution. Eight mole equivalents ofdichlorodifluoromethane, about 4 times the amount of refrigerant thenmetal present to entirely dehalogenate the refrigerant, is allowed toreact until the blue color no longer appears. The temperature of thereaction mixture is then allowed to rise. At about room temperaturefurther destruction of the refrigerant occurs through reaction of onlythe remaining ammonia in the reactor.

While the invention has been described in conjunction with specificexamples thereof, they are illustrative only. Accordingly, manyalternatives, modifications and variations will be apparent to personsskilled in the art in light of the foregoing description, and it istherefore intended to embrace all such alternatives, modifications andvariations as to fall within the spirit and broad scope of the appendedclaims.

We claim:
 1. A method of chemically dehalogenating hydrofluorocarbonrefrigerants comprising the steps of:(a) providing a fluoromethanerefrigerant having at least one hydrogen atom and at least one otherhalogen atom in addition to fluorine, and (b) in absence of a dissolvedmetal reactant reacting said fluoromethane refrigerant with the ammoniaor other nitrogen-containing base to dehalogenate said refrigerant, saidammonia or other nitrogen-containing base being non-aqueous.
 2. Themethod of claim 1 wherein the non-aqueous nitrogen-containing base isliquid ammonia or a solution containing ammonia, said solution beingsubstantially soluble in said refrigerant.
 3. The method of claim 2wherein the solution comprising ammonia is liquid ammonia and an organicsolvent.
 4. The method of claim 1 wherein the non-aqueousnitrogen-containing base is a member selected from the group consistingof refrigerant soluble primary amines, secondary amines and tertiaryamines.
 5. The method of claim 1 wherein the fluoromethane refrigerantis a member selected from the group consisting of chlorodifluoromethane,fluorodichloromethane, chlorofluoromethane, bromofluoromethane,bromodifluoromethane and mixtures thereof.
 6. A method of purifying afluorocarbon refrigerant composition, which comprises the steps of:(a)providing a composition comprising at least two refrigerants, (i) aprimary perhalogenated compound having at least one other halogen atomin addition to fluorine and (ii) a contaminating fluoroalkanerefrigerant compound having at least one hydrogen atom and at least oneother halogen atom in addition to fluorine; (b) reacting the refrigerantcomposition of step (a) with a non-aqueous nitrogen-containing base toselectively decompose said contaminating fluoroalkane refrigerantcompound (ii), and (c) recovering a refrigerant composition from thereaction mixture of step (b), said composition comprising the primaryperhalogenated refrigerant compound (i), said recovered compositionbeing sufficiently free of the contaminating fluoroalkane refrigerant(ii) to enable recycling/reuse.
 7. The method of claim 6 wherein saidnon-aqueous nitrogen-containing base is liquid ammonia or a solutioncomprising liquid ammonia, said solution being substantially soluble insaid refrigerant composition.
 8. The method of claim 7 wherein saidrefrigerant composition of step (a) comprises an azeotrope.
 9. Themethod of claim 8 wherein the refrigerant composition of step (a) is anazeotrope of chlorodifluoromethane and1-chloro-1,1,2,2,2-pentafluoroethane.
 10. The method of claim 7 whereinsaid refrigerant composition of step (a) comprises a mixture of at leasttwo refrigerants having substantially similar boiling points.
 11. Themethod of claim 7 wherein the refrigerant composition of step (a) is amixture comprising dichlorodifluoromethane and chlorodifluoromethane,and the recovered refrigerant of step (c) comprisesdichlorodifluoromethane.
 12. The method of claim 6 wherein saidnitrogen-containing base is a member selected from the group consistingof refrigerant soluble primary amines, secondary amines and tertiaryamines.
 13. The method of claim 12 wherein the refrigerant compositionof step (a) comprises a mixture of dichlorodifluoromethane andchlorodifluoromethane, and the recovered refrigerant of step (c)comprises dichlorodifluoromethane.
 14. The method of claim 6 wherein therefrigerant composition of step (a) is an azeotrope comprisingdichlorodifluoromethane and chlorodifluoromethane, and the recoveredrefrigerant composition of step (c) comprises dichlorodifluoromethane.15. The method of claim 6 including the step of incorporating an organicsolvent into the reaction of step (b).
 16. In a method of chemicallydehalogenating fluorocarbon refrigerants by reacting with a solution ofsolvated electrons formed by dissolving a reactive metal in liquidammonia or other weak nitrogen-containing base, the improvementcomprising the steps of:(a) providing a perhalogenated fluorocarbonrefrigerant having at least one other halogen atom in addition tofluorine; (b) forming a solution of solvated electrons by dissolving inthe liquid ammonia or other nitrogen-containing base a reactive metal inan amount about sufficient to partially reduce the perhalogenatedrefrigerant by removing only one halogen atom therefrom other thenfluorine; (c) reacting the refrigerant of step (a) in the solution ofsolvated electrons of step (b), said reaction being conducted attemperatures sufficiently low as to retard reactions of the solvatedelectrons and liquid ammonia or other nitrogen-containing base withby-products of this reduction reaction, and (d) elevating thetemperature of the reaction mixture of step (c) to initiate furtherdehalogenation by reacting with the liquid ammonia or othernitrogen-containing base.
 17. The method of claim 16 where the reactivemetal is a member selected from the group consisting of alkali metals,alkaline earth metals, aluminum and mixtures thereof.
 18. The method ofclaim 17 wherein the solution of solvated electrons is formed with about2 equivalents of reactive metal per mole of perhalogenated fluorocarbonrefrigerant present.
 19. The method of claim 18 wherein theperhalogenated fluorocarbon refrigerant is a member selected from thegroup consisting of chlorotrifluoromethane, bromotrifluoromethane, andfluorotrichloromethane.
 20. The method of claim 18 wherein theperhalogenated fluorocarbon refrigerant of step (a) isdichlorodifluoromethane.
 21. A method of disposing of hydrofluorocarbonrefrigerants, which comprises the steps of providing a refrigerantconsisting essentially of a fluoromethane compound having at least onehydrogen atom and one other halogen atom in addition to fluorine, andreacting said compound with a nitrogen-containing base to decompose saidcompound, said base being non-aqueous.
 22. The method of claim 21wherein the fluoromethane compound is chlorodifluoromethane and thenitrogen-containing base is ammonia.